Gas-burning boiler and water heater



April 23, 1940.

R. KROGER GAS-BURNING BOILER AND WATER HEATER Filed May 3, 1937 2 Sheets-Shae t 1 Wu (/0 if 11 a 7 w M April 23, 1940.. R. KROGER GAS-BURNING BOILER AND WATER HEATER 2 Sheets-Shet 2 Filed May 3, 1937 Patented Apr. 23, 1940 UNITED STATES i ATENT OFFlCE GAS-BURNING BOILER. AND .WATER HEATER Rudolf Kroger, Niles Center, Ill.

Application May 3, 1937, Serial No. 140,285

6 Claims.v

My invention relates to a gas-burning water heater and boiler, particularly suitable for use in residences and small apartment buildings, for economically supplying either hot water or steam to radiators and for also supplying hot water to bath tubs, for laundry use and for kitchen use.

In general, the objects of my invention are those of providing a gas-consuming appliance of the above type, which will afford the following advantages in comparison with the appliances (or groups or appliances) now commonly used in a given building for the same purposes:

(l) Compactness, simplicity, expeditious manufacture and installation, low cost and low shipping weight.

(2) A unitary appliance affording the above recited two supplies of heated fluid during the cooler months of the year, and also economically supplying only the socalled domestic hot water during the warmer months.

(3) Eflicient utilizing of the thermal units of the gas, with comparatively little waste of heat up thestack, and with substantial elimination of carbon monoxide. I

(4) A speedy initial supplying both of the water or steam for the radiators and of the domestic water, each at a suitable temperature.

(5) Long maintained storage of heat in the appliance during the periods when the operation of the burner is interrupted, to insure a speedy resumption of the supply of adequately hot water or steam when the burner is again operative.

(6) Effective elimination of a reduction in efficiency of the appliance, and of deterioration of parts of the appliance, by the water content of the gas.

(7) Evaporation of nearly. all of the moisture content of the combustion gases before these gases leave the appliance, thereby preventing corrosion of parts of the appliance and allowing this to occur only in the usual horizontal flue leading tothe stack of the building.

(8) Adaptability for use with control devices responsive to room temperature and to the temperature of the domestic hot water, with a maintained thermal storage (during the periods when the gas consumption is nearly shut off) for permitting a speedy resumption of the supply of adequately heated water or steam.

(9) Inexpensive adaptability of a given size of myunitary appliance, during its construction and installation, to operating capacities at which it consumes considerably differing quantities of gas per hour; or for use with oil as the fuel.

( 10) Eff cient operation, regardless of the height of the stack to which my combined water heater and boiler is connected.

In addition, my invention aims to provide Water-heating appliances of. the above, recited characteristics which will be particularly suitable for intermittent actuation of the burners by automatic controls, which will afford a speedy supply of adequately heated water or steam at the initial (early morning) starting of the burners,.and which will retain a store of heated fluid during each interruption of the operation of the burners for insuring a speedy resumption of the supplying of heated fluid whenever the operation of the burners is restarted.

In my United States Patent #2,048,393 ofJuly 31, 1 936,, on a Triple service water heater and boiler I disclosed an appliance for similar purposes, which (at the cost of gas or fuel oil in Chicago and its suburbs) greatly reduced the fuel cost in comparison with that needed when coal or oil are used for the same purpose in the now commercial heating appliances.

However, my said previously patented appliance required the constructing of a separate boiler part (which had to be of copper to pre vent the moisture content of ordinary gas from corroding it), the providing of coiled and difficultly installed steam pipes for superheating the upper portion of the stored hot water, and the supporting of the separately formed boiler within the upper part of the combustion chamber of the appliance. Consequently, the manufacturing cost of this appliance was still undesirably high.

Moreover, with my said earlier type, the condensation of moisture within the draft jacket was sometimes so extensive as to start a corrosion of this jacket, the combustion chamber could not easily be cleaned, and the initial supplying of adequately heated domestic water was somewhat slow. So also, my said earlier appliance could not be easily and inexpensively modified, during itsmanufacture, for efficient operation with different gas consumptions, or for use with oil instead of gas as the fuel.

Illustrative of the manner in which I accomplish all of the heretofore recited objects,

Fig. l is a vertical and diametric section through a gas-burning fluid-heating appliance embodying my here presented invention, taken along theaxisof the air and gas mixing tube of portion of the hollow and thimble-shaped upper compartment of my appliance.

Fig. 3 is a reduced plan section, taken along the line 3-3 of Fig. 1, showing the horizontal combustion gas ducts which extend through the lower part of the said upper compartment to connect the combustion chamber with the lower part of the annular draft space surrounding the riser wall of this upper compartment.

Fig. 4 is a reduced plan section taken along the line 4-4 of Fig. 1.

Fig. 5 is an enlarged vertical section throughthe outer end portion of one of the arcuate combustion gas ducts and adjacent parts,- showing the draft-checking baffle mounted in the outer end of this duct.

Fig. 6 is a fragmentary elevation, taken from the line 6-6 of Fig. 5. i a

Fig. 7 is a reduced elevation of the lower portion of my appliance, taken from the right-hand side of Fig. l.

Fig. 8 is a similarly reduced perspective view of the lower water compartment which supports the heating element.

Fig. 9 is a reduced central and vertical section, taken in the same plane as Fig. 1, showing the vitreous fire-box lining needed in the lower compartment when an oil burner is used in my appliance.

In the illustrated embodiment of my invention, the lower water compartment I of my appliance is an axially upright hollow ring which has a doorway 2 formed in its forward side, as'shown in Fig. 8, through which a main burner and shutter assembly extends so as to dispose the burner coaxial with the said ring and above the floor on which the lower compartment is seated. As here shown, this burner includes a gas-andair mixing tube T leading to an annular outlet around a flame spreader 3 housed by a cup-like flame confiner 4 which aids in directing the flame mainly upwards. 1 The mixing tube T as well as the gas-supply tube G are supported by a casting 7 (also seated on the said floor) which effectively closes the entrance to the said doorway. This casting includes a main shutter portion S through which air is admitted to the doorway for mingling with the flame from the main burner, and also an upper air inlet for admitting air to the mixingtube,

the latter inlet being controlled by a secondary shutter 5. i Disposed within the said doorway above the mixing tube is a partitioning member, supported by lugs (Fig. 8) on the two sides of the doorway. This includes a horizontal partition P, and an upright partition P rising from theforward end of the part P, this part P being formed and disposed so that air can flow upwards along the line 6 of Fig. 1 behind the rear end of this part.

, Seated on the same horizontal partitioning part is a secondary burner b for which the just men- I tioned air-is supplied, which directs flame against the doorway top l above it, the upright partition part P being sufficiently short so that the combustion gases from the secondary burner can issue above it (along the line 1) into the combustion chamber C of the appliance.

For the boiler section of my appliance I provide a hollow-walled thimble-shapedupper compartment seated upon and alining axially with the lower compartment I. This upper compartment has its outer riser wall 8 of smallerdiameter than the outer riser wall I of the lower compartment, and has the vertical spacing 9 between the upper and lower walls of its thimble top portion considerably greater than the spacing l0 between the two tubular walls 8 and H of its riser portion, the interior diameters of the superposed tubular riser walls II and H being preferably identical.

Freely housing the said upper compartment is a thimble-shaped draft-jacket which has the lower end of its riser wall J seated upon and sealed to the top of the lower compartment, and which has its top J provided with a central draft outlet opening into a header H mounted on the.

said jacket top. Thus disposed, the said jacket affords a tubular draft space D connected to the interior of the said header by an upper draft V space 13, so that these two draft spaces together form a unitary thimble-shaped draft space.

The lower part of the said tubular draft space D is connected with the combustion chamber (bordered by the inner faces of the riser walls H and II of the two compartments) by aset of lower and preferably horizontal combustion gas ducts L. These ducts extend radially of the axis of the upper compartment through the hollowwalled riser portion of the latter compartment, and preferably are uniformly spaced circumferentially of that compartment (as shownin Fig, 3) to equalize the distribution of the combustion gases in the tubular draft space D.

In addition to the said lower ducts L, I provide a plurality of upper gas ducts U, which lead from the top head Me of the thimble-top portion of the combustion compartment 0 to the said thimbleshaped draft space D, and which have their outlets at a considerably higher elevation than the said head H These upper gas ducts preferably have arcuate axes spaced uniformly about the vertical axis of the upper compartment and have their outlets in the upper portion I4 ofthe outer riser wall 8 of that compartment, the total bore area of the lower gas ducts preferably being larger than that of the said upper ducts. Moreover, these upper gas ducts U preferably are in relatively staggered relation to thelower gas ducts L, as shown by a comparison of Figs. 2 and 3.

When the main burner of my appliance is in operation, the upward draft due to the usual connection of the header H to a (not illustrated) stack through a flue pipe F draws the flame as well as the combustion gases from the burner mainly upwards, so that the major portion of the hottest gases reach the top head M or the thimble top of the upper combustion compartment. Consequently, these hottest gases flow through the arcuate upper gas ducts U; and in thereafter passing upwards through the upper part of the tubular draft space D, these gases produce an upward suction within the just named draft space so as to draw combustion gases through the horizontal gases ducts L from the lower portion of the same draft space.

Owing to the effect of this suction, I cause combustion gases to move upwards along the exterior of theupper portion I4 of the outer riser wall 8 of the upper compartment at a much slower rate than the gases which move upwards superheat the steam above that water level,

thereby speeding the production of a sufficient head of steam.

However, if each upper gas 'duct U had its outlet of the same diameter as the remaining portion of its bore, the flow of combustion gases through the said upper ducts would be too rapid (when my appliance is used with gas as the fuel) to allow these gases to transfer an adequate proportion of their heatthrough thewalls of the tubes to water or steam in the corresponding portion of the thimble-shaped upper compartment. For that reason, I suitably reduce the area of the outlet end of each such upper duct,

, to an extent proportioned to the normal rate gas consumption of the gas burner.

As a simple provision for this purpose, I

throttle each such duct outlet (as shown in Figs.

and 6) by fitting into it a baffle plate B having a recess IS, the area of which recess is suitably less than half that of the said duct outlet end, each such bafile preferable being inserted so that the said recess is at itsupper edge. By thus restricting the outlet of each upper duct I decidedly slow up the flow of combustion gases through each such duct, thereby allowing ample time for utilizing the heating effect of these gases on the large interior surface area which each such duct affords when of a bore much larger than the area of the outlet recess I 6. To obtain this ample heat transfer time I preferably make each upper gas duct of a length at least six or eight times the diameter of its bore. Moreover, by attaching each such balflel plate so that its outlet recess is at the top, as shown in Figs. 5 and 6, I cause the stack draft to draw the gases toward the upper edge of each arcuate duct, so that each duct conveys a considerable portion of the heat of its gaseous content upwardly into the fluid which is to be heated.

By thus retarding the rate of flow through the upper ducts U, I also enable the previously recited upward suction in the tubular draft space D to draw an adequate. portion of the total combustion gases into the lower portion of that space through the lower ducts L; and by disposing the upper and lower gas ducts in relatively staggered relation, I substantially equalize the distribution of the rising gases circumferentially of the exterior of the upper compartment.

In the customary winter use of my appliance, the lower compartment is kept entirely filled with Water which enters near the bottom of that compartment through a cold water pipe I1, and which issues as hot water through a domestic Water supply pipe 18 when the valve [9 is open. However, the upper compartment (when used for supplying steam to radiators) is filled with water only to a level Z above the top head M of the combustion compartment and below the midheight of that portion, as for example to the level L in Fig. 1, which level can be seen in the usual water gauge 24. Water, such as that which has condensed in the radiators, is admitted to the lower portion of this upper compartment through an inlet pipe 20, the hereafter described connection between the two compartments by a pipe 2| being shut off by a then closed valve 22.

When both burners are first actuated, as for example at early morn through the usual thermo-electric control means employed by heating engineers for making such 'a heating appliance responsive to the temperature in a given room of the house, the main burner effects a heating of the upper compartment much more than the lower one. However, since the secondary burner b underhangs an upper part of the lower compartment, this burner adds its heating effect to the upper part of the water in the latter compartment so as to expedite the supplying of adequately heated domestic water through the domestic Water pipe I8.

In the upper compartment, the generally upward travel of the hot combustion gases toward the head M of the thimble top of that compartment efiect a speedy heating of the part of the water above the head or plate I4 particularly when the level of this water (which can readily be checked by a water gauge 24) is at only a short distance above the said plate. C'onsequently, steam soon forms in this compartment and this steam is superheated by the radiation of heat to it from the major portions of the lengths of the upper gas ducts U, so that I obtain a speedy supply of steam to the steam pipe 25 which extends upwardly from the top of the upper compartment through the otherwise closed top of the header H.

To prevent material heat losses from my appliance to the air surrounding it, I surround the exposed portions of my heretofore described appliance, except the header H and the projecting portions of the burner and air inlet assembly, with a layer of, heat-insulating material 26 sheathed by a metal casing 2'7, here shown as including a slidably attached casing top 21 I also providev one side of the appliance with a sight tube 28 alining with one. of the lower gas ducts L, the outer end of which is closed by a pane 29 through which the flame within the combustion chamber can be observed. In addition, I provide a horizontal tube 39 extending radially outward from the combustion chamber at an elevationbetween that of the lower gas ducts L and the plate M the outer end of this tube 3!] being normally closed by a pivoted flap 3!. This tube 30, when of a sufficiently large size to admit a mans arm, allows both the upper and the lower gas ducts to be cleaned with a suitable brush when needed.

In addition, I usually attach a so--called aquastat thermostaticdevice 32 to the lower compartment, desirably at about the. midheight of the latter, for connection (in a manner well known to heating engineers) with a control for the secondary burner b, so as to throttle that burner when the average temperature of the store of domestic hot water reaches a predetermined maximum-as for example 140 degrees Fahrenheit.

With my heretofore described construction, the baffling of the outlet ends of the upper gas ducts insures a complete vaporizing of the moisture content of the major part of the combustion gases while these gases are flowing through the said upper ducts. Likewise, owing to the upward suction in the riser portion D of the draft space, nearly all of the moisture in the gases which flow through the lower gas ducts is carried upwards and evaporated while passing the steam-containing part of the upper compartment. Consequently, nearly all of the moisture content of the gas fed to the burners passes as vapor into the header H and thereafter into the (desirably approximately horizontal) flue pipe F; and since this pipe is at a temperature somewhat above the boiling point of water during the winter operation of my appliance, this pipe conveys the water vapor to the chimney or stack to which that pipe leads.

.I-Iowever, since the lower gas ducts L are at higher elevation than the bottom ofthe thimble-shaped unitary draft space D, some water collects in the bottom of the said space; and to prevent even this from having a corrosive action I provide seepage openings (such as the recess 34 of Fig. l) at the lower end of the jacket J, through which such seepage can flow into the adjacent packing 26. This seepage then is gradually evaporated by the warmth of the said jacket, andthe looseness of the casing cover 2,1 allows a ready escape of the resulting vapor into the air above the appliance.

During the warmermonths of the year, when no heated fluid is needed for radiators, the two compartments can readily be operated conjointly for economically supplying the needed domestic hot water. To do this, the valves l9 and 22 are closed, as also the upper valve 36, and the hot water is then supplied through a pipe 31 when the valve 38 is opened.

Moreover, with either the winter or the summer operation, my app1iancewhen proportioned substantially as illustratedstores a large amount of well-heated water during each operation of the main burner, so that an effective renewal of a supply of adequately heated fluid occurswithin a quite short time after the end of a thermostatic throttling of the main burner.

With the various parts of my appliance suitably proportioned, as in Fig. 1, I have obtained the following results:

(A) A combustion efficiency of fully 86 percent with gas, and slightly lower with fuel oil, attested both by comparisons of the heat units iii the consumed gas with those of the hot fluid supplied by my appliance, and by thenegligibly small amount of carbon monoxide in the stack to which the flue pipe leads.

(B) A maximum stack temperature of about 280 degrees, with the flue pipe F usually below 250 degrees (both Fahrenheit).

(C) About 28 percent reduction in cost, in comparison with the appliance of my said previous patent.

(D) Unusual compactness, as for example the supply of steam for '750 square feet of radiation, or hot water for 1200 square feet of radiation, with my appliance of 31 inch diameter and with its casing 52 inches high.

(E) Adaptability to varying gas consumptions by the mere selection of baflles with different sizes of recesses, as from 150 to 250 feet per hour, by making the baflle recesses of the areas indicated respectively at l5, l5 and l5 in Fig. 6.

(F) Adaptability for use with oil as the fuel, by merely omitting the baffles B, providing a refractory lining M (Fig. 9) for the bottom and all except a small upper portion of the firebox, and substituting a gravity fed oil-burner for the main burner of Fig. 1, the secondary burner being then omitted.

(G) Substantial absence of any corrosion of parts of the appliance itself, and a quite slow action of corrosion on the flue pipe F which can easily be replaced at a small cost.

(H) An unusually speedy supplying of steam or hot water to radiators or the like, both after the initial starting of the main burner in the morning and after each period during which this burner was throttled.

(I) Unusually low consumption of fuel in proportion to the heat units of the fluid supplied by the appliance, due both to the high combustion efiiciency, the effective storage of large quantities of heated fluid during the interruption of burner operation.

(J) Ease of cleaning the appliance, since both sets of combustion gas ducts can be reached through the clean-out tube 30, and since the entire burner unit can be slid out of the appliance for cleaning the lower part of the combustion chamber if this should become necessary.

To permit the above recited superheating action of the upper gas ducts to be. highly efiective, I preferably make the vertical spacing between the top and bottom walls of the thimble-top portion of the upper compartment at least as large as the interior radius of the inner tubular riser portion of that compartment.

However, while I have heretofore described my water heating appliance in connection with an embodiment including many desirable details of construction, proportioning and arrangement, it should be obvious that many changes may be made without departing either from the spirit of my invention or from the appended claims.

While the constructing of a water heating appliance having a hollow-walled thimble-shaped water container freely housed by draft jackets, and also having gas ducts leading from the top of the combustion chamber to the riser portion of such a draft jacket is not new in itself, heretofore proposed types have not been designed for speeding the production of hot water, for superheating steam in a steam dome part of the appliance, for using heat of part of the combustion gases to heat the generally imperforate outer riser wall of the water container, for avoiding an undue retardation of the draft of the combustion chamber with a low fire, or for adequately utilizing convection currents for carrying heated water upwards. My present invention aims to avoid all of the just recited shortcomings by means of simple, adequate and suitable co-operating structural features.

I claim as my invention:

1. A fluid burning water heating appliance, a hollow-walled and thimble-shaped water container, the bore of which forms the upper and major portion of the combustion chamber of the appliance, a thimble-shaped draft jacket housing the said container and freely spaced from the container to afford both an annular draft space around the riser wall of the container and an upper draft space overlying the top of the container, the draft jacket having an outlet leading from the central part of said upper draft space; a set of horizontal lower combustion gas ducts extending radially of the container and at a substantially common level through relatively low portions of the riser part of the thimble-shaped container for connecting the combustion chamber with the lower part of the said annular draft space; and a set of upper combustion gas ducts leading upwards and radially outward of the water container from the thim ble-top portion of the container, and opening through outlets in the outlets riser wall of the container near the upper end of the said wall; the saidtwo sets of gas ducts forming the only combustion gas ducts leading from the said combustion chamber and baflle means in the upper ducts arranged to substantially reduce flow area through said upper ducts as compared to the flow area through the lower ducts.

2. A water heating appliance as per claim 1, in which each of the upper combustion gas ducts has a length at least five times the diameter of its bore, the baffle associated with the outlet end of each such upper duct reducing the outlet area of that duct to less than half the area of the remaining portion of the bore of the duct; whereby the said restriction of the upper duct outlets retards the rate of gas flow through the said outlets so as to increase the length of the heattransfer time from the said ducts to fluid in the part of the water container portion which is above the top of the combustion chamber, and whereby the said retarding of the. gas flow through the upper gas ducts also allows time for the evaporation within the said ducts of moisture in the combustion gases.

3. A waterheating appliance of the class in which an upright hollow thimble-shaped boiler isseated upon and co-axial with a hollow annular water heater, in which the bores of the said thimble-shaped boiler and the said water heater conjointly form the combustion chamber of the appliance, and in which, the said water heater bore houses a burner; the said appliance being characterized by having one side portion of the annular water heater provided with an air-admitting doorway leading to the bore of the water heater, the water heater having a water-containing portion overlying a part of the said doorway; and including an auxiliary heater disposed in the said doorway and disposed for the said two baffles being so disposed with re-" spect to the walls of the doorway as to cause part of the air admitted to the chamber to flow above the first named bafiie and the heater and thereafter into the upper portion of the bore of the annular water heater.

5. A fluid burning water heating appliance, a hollow-walled and thimble-shaped water container, the bore of which forms the upper and major portion of the combustion chamber of the apliance, a thimble-shaped draft jacket housing the said container and freely spaced from the container to afford both an annular draft space around the riser wall of the container and an upper draft space overlying the top of the container, the draft jacket having an outlet leading from the central part of said upper draft space; a set of horizontal lower combustion gas ducts extending radially of the container and at a substantially common level through relatively low portions of the riser of the thimble-shaped container for connecting the combustion chamber with the lower part of the said annular draft space; and a set of upper combustion gas ducts leading upwards and radially outward of the water container from the thimble-top portion of the container, and opening through outlets in the outlets riser wall of the container near the upper end of the said wall; the said two sets of gas ducts forming the only combustion gas ducts leading from the said combustion chamber, each set of ducts having the axes of its constituent ducts in upright planes intersecting on the thim ble axis of the container, and having the outlet ends of the ducts uniformly spaced circumferentially of the container; and the outlet ends of the ducts of the two sets being relatively staggored, so that the upward draft produced along the outer riser Wall of the water container by the issuing of combustion gases from the upper combustion gas ducts will distribute the gases issuing from the lower gas ducts over portions of the said riser wall which are not directly above the outlets of the said lower ducts, the said two sets of tubes constituting the only gas passages leading from the combustion chamber.

6. A fluid burning water heating appliance, a hollow-walled and thimble-shaped water container, the bore of which forms the upper and major portion of the combustion chamber of the appliance, a thimble-shaped draft jacket housing the said container and freely spaced from the container to afford both an annular draft space around the riser wall of the container and an upper draft space overlying the top of the container, the draft jacket having an outlet leading from the central part of said upper draft space; a set of horizontal lower combustion gas ducts extending radially of the container and at a substantially common level through relatively low portions of the riser part of the thimbleshaped container for connecting the combustion chamber with the lower part of the said annular draft space; and a set of upper combustion gas ducts leading upwards and radially outward of the water container from the thimble-top portion of the container, and opening through outlets in the outlets riser wall of the container near the upper end of the said wall; the said two sets of gas ducts forming the only combustion gas ducts leading from the said combustion chamber, and a baflle extending across the outer end of each upper gas duct, the baflle having at its upper edge a recess of an area less than half that of the remainder of the bore of the said duct.

, RUDOLF KROGER. 

